Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously reported that CR-Fc, an Fc chimeric protein containing the cysteine-rich (CR) domain of the mannose receptor, binds to marginal zone metallophilic macrophages (Mo) and B cell areas in the spleen and to subcapsular sinus Mo in lymph nodes of naive mice (CR-Fc(+) cells). Several CR-Fc ligands were found in spleen and lymph node tissue lysates using ligand blots. In this paper we report the identification of two of these ligands as sialoadhesin (Sn), an Mo-specific membrane molecule, and the leukocyte common antigen, CD45. CR-Fc bound selectively to Sn purified from spleen and lymph nodes and to two low molecular weight isoforms of CD45 in a sugar-dependent manner. CR-Fc binding and non-binding forms of Sn, probably derived from CR-Fc(+) and CR-Fc(-) cells respectively, were selected from spleen lysates. Analysis of the glycan pool associated with the CR-Fc-binding form revealed the presence of charged structures resistant to sialidase, absent in the non-binding form, that could correspond to sulfated structures. These results confirm the identification of the CR region of the mannose receptor as a lectin. We also demonstrate that the same glycoprotein expressed in different cells of the same organ can display distinct sugar epitopes that determine its binding properties.
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PMID:Cell-specific glycoforms of sialoadhesin and CD45 are counter-receptors for the cysteine-rich domain of the mannose receptor. 1057 6

Interactions of oral streptococci and actinomyces with polymorphonuclear leukocytes (PMNs), mediated by sialic acid- and Gal/GalNAc-reactive adhesins, respectively, result in activation of the PMNs and thereby may contribute to the initiation of oral inflammation. Sialidase treatment of PMNs or HL-60 cells abolished adhesion of Streptococcus gordonii but was required for adhesion of Actinomyces naeslundii. The same effects of sialidase were noted for adhesion of these bacteria to a major 150-kDa surface glycoprotein of either PMNs or undifferentiated HL-60 cells and to a 130-kDa surface glycoprotein of differentiated HL-60 cells. These glycoproteins were both identified as leukosialin (CD43) by immunoprecipitation with a specific monoclonal antibody (MAb). Adhesion of streptococci and actinomyces to a 200-kDa minor PMN surface glycoprotein was also detected by bacterial overlay of untreated and sialidase-treated nitrocellulose transfers, respectively. This glycoprotein was identified as leukocyte common antigen (CD45) by immunoprecipitation with a specific MAb. CD43 and CD45 both possess extracellular mucinlike domains in addition to intracellular domains that are implicated in signal transduction. Consequently, the interactions of streptococci and actinomyces with the mucinlike domains of these mammalian cell surface glycoproteins result not only in adhesion but, in addition, may represent the initial step in PMN activation by these bacteria.
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PMID:Identification of polymorphonuclear leukocyte and HL-60 cell receptors for adhesins of Streptococcus gordonii and Actinomyces naeslundii. 1103 44